Many electronic systems, such as telephone switching stations, or robotic manufacturing facilities, require extensive electronic circuitry for their operation. Frequently, the electronic circuitry is implemented in the form of numerous, interconnected, printed circuit boards. These printed circuit boards, commonly called xe2x80x9ccardsxe2x80x9d or xe2x80x9cpacks,xe2x80x9d are often mounted in card cages, which are themselves supported by racks. FIG. 1 is a simplified example of a card cage 3, supported by a rack 6, and containing cards 9.
The individual cards often contain visual signal indicators, which provide information to technicians. For example, each card 9 of FIG. 1 may be equipped with an LED 12 which acts as a xe2x80x9cpilot light,xe2x80x9d indicating whether the card is receiving electric power. Some cards 9 may be equipped with switches 13 which control power delivery to the card 9. As another example of an indicator, each card 9 may be equipped with a second LED 15, which indicates whether a certain type of fault has occurred in the card.
Regarding fault indication, some cards 9 include circuits in pairs, namely, a primary circuit and a back-up circuit (not shown). An LED indicator, such as indicator 15, provides three pieces of information about the pair, for example:
1. If neither circuit has experienced a fault, the LED indicator will display a green color.
2. If the primary circuit has experienced a fault, so that the back-up circuit has taken over operation, the LED indicator will display a yellow color.
3. If both the primary circuit and the back-up circuit have experienced faults, the LED indicator displays a red color.
In addition to cards 9, in the general case, the card cages 3 can include other equipment. Apparatus 18 illustrates a generic type of additional equipment. This apparatus 18 includes visual indicators, such as meter 21 and an LED bar graph 24. This apparatus 18 also includes dual-function controls, such as rotary dials 27 and switches 30. These latter components are termed dual-function, because they perform a control function, as by selecting a switch position in the case of rotary dials 27, and they also act as visual indicators, by visually indicating the position presently assumed by the switch. This apparatus can also include connectors 28 which connect with various components of the rack 6.
Two specific examples of such additional equipment 18 are (1) a power supply and (2) a testing-and-control center, which provides jacks and test ports which connect with all of the cards, to which test equipment can be connected.
Management systems exist which allow a person, located remotely from the cards themselves, to view an image of the cards, including an image of the visual signal indicators. FIG. 2 is a representation of such an image, called a xe2x80x9cshelf view,xe2x80x9d which is displayed on a computer monitor 36. Conceptually, the image resembles a television picture produced by a video camera which is focused on the cards 9 of FIG. 1.
However, the management systems, in general, do not actually use video cameras. Instead, they synthesize the image shown in FIG. 2, from two sources. One source is data which represents the basic visual appearance of the cards 9, but not of the indicators, such as LED 12. This data can take several forms.
One form is a bit-map, which can be derived from digitizing a photograph of the cards. Another form is a vector-map, which can be produced by a skilled artist who manually sketches the cards, as by using Computer Aided Drafting (CAD) software, or by tracing a photograph of the cards, using the same software. A significant feature of these forms of the image is that they are xe2x80x9cstatic,xe2x80x9d since they do not change, as time progresses.
Superimposed over the static images is a xe2x80x9cdynamicxe2x80x9d image, which represents the current state of the signal indicators. In FIG. 2, for example, the image 15A may be displayed in the color red, thereby indicating the color shown by the actual LED 15 of FIG. 1. This color red can change with time, as the color of actual LED 15 in FIG. 1 changes.
In the more general case, as indicated in FIG. 2, additional visual indicators can be displayed, including switches 13 and 30, and the positions of rotary dials 27. In addition, if a particular card is absent, the slot previously occupied by the card is indicated by a greyed-out rectanngle 37.
The management system is used to troubleshoot problems occurring in the cards 9. In a telephone switching station, thousands of cards may be contained in a single building, which is staffed by a single technician. Many such buildings are under control of a central office.
When a problem occurs in one of the buildings, an expert, located at the central office, and using the shelf view of FIG. 2, locates faulty cards, and guides the technician through the process of replacing the faulty cards.
However, the effectiveness of such management systems depends, in part, upon whether the display 36 in FIG. 2 accurately represents the visual appearance of the card cage of FIG. 1. For example, a technician may replace a card 9 with another card having a different appearance. For the display 36 of FIG. 2 to reflect this change, data indicative of the visual appearance of the new card must be supplied to the workstation. Otherwise, the shelf view of FIG. 2, seen by the expert located at the central office, will not correspond with the actual card cage seen by the technician, and confusion will result.
In one form of the invention, data indicative of the visual appearance of printed circuit cards, which are mounted in a rack, is stored at the site of the rack. Upon request, selected data is transmitted to a remote party.